The present invention relates to write performance in clustered file systems. More specifically, the invention relates to integrating a file system cache of a clustered storage system with a distributed memory layer to enable efficiency of synchronous write transactions.
Workloads with a plurality of synchronous write operations or a high ratio of commit operations are known to suffer performance penalties. These workloads are common in database workloads with a high ratio of commits. Similarly, web based workloads perform a series of file operations requiring a commit to stable storage when closing a file. Virtual machines have their own block layer, and all write transactions arriving to an underlying storage in the virtualized environment are synchronous and require immediate commit to a stable storage. Each of these operations requires workload data to be written to a storage subsystem before returning an acknowledgement to the client. The performance penalties are reflected in increased write latency because disk access latencies are orders of magnitude higher than dynamic RAM (also referred to herein as DRAM) latencies. In addition, commit operations do not allow the file system to delay a write transaction by gathering a plurality of the write transactions into a single I/O to a storage subsystem. Accordingly, various types of operations that require writing data to a storage subsystem and an associated acknowledgement communication are affected by performance penalties.